The present invention relates to an lengthwisely adjustable fluid spring with a cylindrical casing, with end pieces of which each one is fitted in one end of the casing, and with a control unit, which is arranged in a cavity of one of the end pieces, said control unit comprising at least two sealing devices and one actuating lever linking said devices.
Such fluid springs are already known and are used e.g. on chairs having seats with adjustable height. The fluid can be a liquid or air. The fluid spring contains a piston inside. The cavity of the end piece connects to the interior of the fluid spring. Further then, a duct connects to the cavity. The duct""s far end is linked to the second end piece. This second end piece has an inner canal which stretches between the close end of the overflow port and the interior of the fluid spring.
The flow of fluid between the two sides of the piston is controlled by the control unit whose main part is arranged in the cavity of the first end piece. The actuating lever of this known fluid spring is worked as a straight rod which is positioned vertically along its entire length.
One section of the rod rises axially from the upper side of the fluid spring. The sealing devices being part of this arrangement are fixed at the actuating lever, such as that one sealing device is beneath the other and that they both run in parallel. Due to this type of construction, the height of the stool is enlarged. However, at least in some instances, such a big height of the fluid spring is undesirable.
The object of the present invention is to remove the said as well as even further disadvantages of the fluid spring as it is known.
This object is solved, according to the present invention, with a fluid spring of the foregoing mentioned type as specified in the characterising portion of the patent claim 1.